Why are Maryland Democrats coalescing behind Alsobrooks over Trone?

[Woody]

Haven't paid much attention to the race, but at first glance it's bizarre that a county executive (not even the most populous county in the state) has virtually the entire party and statewide officials backing her over a sitting congressman. Even Trone's colleagues in the delegation is backing Alsobrooks, with the exception of Ruppersberger, who is retiring anyway.